DE3429419A1 - DRILLING TOOL FOR HAND DRILLING MACHINES - Google Patents

Abstract

A drill bit with an axially elongated shank is suitable for use in all known conventional hand-held drilling machines. The shank is generally cylindrically shaped with axially extending first grooves open at the free rear end face of the shank. Axially extending second grooves are superimposed at least in part on the first grooves and are spaced from the rear end face. Each second groove forms at least one shoulder face disposed transversely of the shank axis and oriented in the direction facing oppositely to the rear end face. Accordingly, the drill bit, due to its first grooves, can be utilized in the chucks presently used in drilling machines and percussion drilling machines. Further, due to the second grooves, the drill bit can be clamped for limited axial movement in the chucks of known hammer drills.

Description

BERG - STAPF SCHWABE · SANDMAJB

PATENTANWÄLTE MAUERKIRCHERSTRASSF. 45 8000 MUNICH 80 3429419

Attorney File 33 654 August 9, 1984

HILTI Aktiengesellschaft

FL-9494 Schaan Principality of Liechtenstein

DRILLING TOOL FOR HAND DRILLING MACHINES

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* (089) 9882 72-74 Telex: 524560 BERG d Bank accounts: Bayer Vereinsbank Munich 453100 (BL7 70020? 70)

Telegrams (cable): Fax: (089) 983049 Hypo-Bank Munich 4410122850 (BLZ 700 20011) Swift Code: H / PO DE Ml

BERGSTAPFPATENT Miinchpn KaIIe Infotec 6350 Gr. Il + III Postscheck Munich 65343-808 (BLZ 70010080)

HILTI AKTIENGESELLSCHAFT IN SCHAAN Principality of Liechtenstein

Drilling tool for hand drills

The invention relates to a drilling tool for hand drills, with a substantially cylindrical insertion end.

The well-known, the production of holes in hard underground materials, such as concrete, stone and the like, hand-held drills can essentially be divided into three groups subdivide into drills, impact drills and rotary hammers.

The pure drilling machines, which are of minor importance today, are simple hand-held devices, which just give the drilling tool a rotary movement. These devices show how to use the drilling tool a chuck in which the generally cylindrical insertion end of the drilling tool is clamped can.

The hammer drilling machines also have a chuck in which the drilling tools are clamped as mentioned above can. In contrast to the simple drills the chuck is arranged on an axially movable spindle in the hammer drills, on which during the Drilling process, a vibratory movement is exerted .. This vibratory movement is through internal means, such as Ratchet washers, generated and transferred from the chuck to the drilling tool firmly clamped in it.

The rotary hammers are by far the most important today. These devices also have a chuck in which, in contrast to drills and impact drills the drilling tool is axially movable to a limited extent, but is held in a form-fitting manner for the transmission of the rotary movement. A hammer piston is moved back and forth by means of the device, such as in particular an electropneumatic hammer mechanism, which directly or with the interposition of a transmission bolt, for example, the drilling tool an impact movement granted. Due to the axial mobility in relation to the chuck, no impact movement is transmitted to the latter, so that the entire impact energy is available for the drilling process.

For positive clamping of the drilling tools in rotary hammers, it is common to use the drilling tools with a standard spigot end to provide the driving surfaces for radially displaceable Having locking elements of the chuck. Since such a unit insertion end has led to a sharp increase in the cost of drilling tools, are in recent times Solutions with variable spigot ends have become known. These are in turn in Chucks clamped, such chucks have a variable guide area and mating surfaces for the driver surfaces have on the drilling tools.

Having hammer drills are very essential compared to impact drills have application advantages, and the drilling tools are increasing by creating variable insertion ends economically more interesting / takes place in considerable Extent of a replacement of the impact drills by the hammer drill. Thus the situation occurs increasingly that one and the same user is in possession of both impact drills and rotary hammers. There one Users, following the future trend, usually only buy drilling tools for hammer drills, lies the requirement to use these drilling tools in the hammer drills still in his possession to be able to.

To solve this problem, a drilling tool is known whose insertion end is grooved in such a way to create the driver surfaces has distributed that clamping jaws of a chuck cannot fall into the grooves if such a drilling tool is used in a hammer drill. This creates the same situation as when using a drilling tool a cylindrical spigot end is clamped in a hammer drill, ie must be due to the pure frictional connection considerable clamping forces are applied by the chuck. After axially only a vibratory movement on the drilling tool acts, the forces acting in this direction are irrelevant, but all the more forces that act are required for the transmission of the torque. Provided that the clamping forces from the chuck are not sufficient are applied, there is a risk that the torque will not be fully transmitted to the drilling tool, and the drilling tool can twist within the chuck. This combination tool probably fulfills the task of that it can be used universally in the device types of interest, but leads to an application in Impact drills do not result in any further improvement over conventional tools.

In order to improve drilling tools in this regard too, is Another solution has become known, according to which the spigot end has a relatively long groove closed towards the rear face to create driver surfaces. While using such a drilling tool in a hammer drill the same situation as the one described above Drilling tool occurs, this formation of the groove should be an improvement when used in impact drills be achieved. With a limited number of chucks, ie with those chucks where the rear edge of the clamping jaws a sufficient distance from the chuck-side stop surface for the rear face of the drilling tools have, an advantage is achieved in that the clamping jaws completely into the grooves at the insertion end of the drilling tool can immerse yourself. In the case of a large number of chucks on the market, there is no such distance present so that the jaws are due to the application the rear end of the groove, which is required for rotary hammers, cannot be immersed. This creates besides The disadvantage of the in turn insufficient rotational drive is another significant disadvantage that arises as a result comes that the insertion end of the drilling tool only comes into contact with the clamping jaws over a very short distance and this creates a kind of ball joint, which leads to a considerable runout of the drilling tool.

The invention is based on the object of a simple to manufacture To create a drilling tool that, when used in all hand drills, has a sufficient holder and leads to sufficient concentricity.

According to the invention, the object is achieved by a drilling tool, which is characterized by the combination of the following features.

a) The insertion end has one or more longitudinal grooves open towards the rear face.

b) The insertion end has one or more longitudinal grooves arranged at a distance from the rear face on.

c) Longitudinal grooves that are open towards the rear face and are spaced from the rear face overlap in their axial projection to form a face facing away from the rear face At least part of the shoulder surface.

By the combination features proposed according to the invention becomes at least one longitudinal groove open towards the rear face with at least one towards the rear face towards the closed longitudinal groove overlaps in such a way that, in a certain sense, one or more double functional grooves are created. The longitudinal groove, which is open towards the rear face, ensures that the clamping jaws of any type of chuck be able to immerse completely and thus, in addition to the rotary drive, sufficient, decisive for the concentricity of the drilling tool Create leadership. In particular, that circumstance is taken into account here according to which the axial mounting of drilling tools is of secondary importance when used in impact drills and compared to Rotary driving can be easily accomplished by pure frictional connection.

When using the drilling tools in rotary hammers, in addition to the torque transmission, the creation of a limited one However, axial mobility is crucial. This is achieved in a chuck, along with a variable guide area Gegenflächen'an has projections that are below radial adjustment can plunge into the longitudinal grooves arranged at a distance from the rear face. the Mobility is limited by shoulder surfaces, basically only the shoulder surface which is proposed according to the invention and which faces away from the rear end face has a meaning. As the following execution

show, this shoulder surface can be characterized by various Formation and overlapping types of the longitudinal grooves come about.

According to a proposal of the invention, both types of Longitudinal grooves have essentially the same cross-sectional area, with shoulder surfaces due to the only partial overlap develop. In contrast, according to a further proposal, the longitudinal groove open towards the rear face can be used have a smaller cross-sectional area than the longitudinal groove arranged at a distance from the rear end face. Through this shoulder surfaces arise even with a symmetrical arrangement of the longitudinal grooves.

Since the shoulder surfaces turn out to be relatively small with a symmetrical arrangement of the longitudinal grooves, there is also longitudinal grooves with a different cross-sectional area the possibility of an only partial overlap. A preferred embodiment This only partial overlap consists in the fact that the longitudinal grooves open towards the rear face offset against the direction of rotation of the drilling tool to the longitudinal grooves arranged at a distance from the rear face are arranged. This offset together with the different cross-sectional areas of the longitudinal grooves leads to a considerable Enlargement of the shoulder surfaces, especially if for reasons Adequate guidance of the drilling tools when used in impact drills is based on the requirement is that the groove bottom of the longitudinal groove open to the rear face of the one at a distance from the rear The longitudinal groove arranged on the front face must not be interrupted. The suggested direction of dislocation represents ensure that the shoulder surface facing away from the rear face comes to rest on the side where due of the torque acting on the drilling tool, opposing surfaces of projections of the chuck predominantly come to the plant. The creation of such shoulder surfaces has a positive effect on the service life of the insert

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end with the predominant use of drilling tools in rotary hammers the end. Taking into account the different diameters of the spigot ends as well as the dimensions and shape of the In the longitudinal grooves, an angular offset of the order of magnitude of 8 to 15 ° has proven to be useful.

Based on an already used in rotary hammers Tried and tested other drilling tool is also proposed along a longitudinal groove that is open towards the rear end face to provide one or more longitudinal grooves arranged at a distance from the rear face. In particular, it will the advantage achieved is that the number of shoulder surfaces and thus the entire stop surface for the axially limited mobility the drilling tools are enlarged when used in rotary hammers. As a compromise solution, on the one hand from the From the point of view of the number of shoulder surfaces and, on the other hand, from the point of view of the manufacturing effort, in particular two longitudinal grooves arranged at a distance from the rear face have proven successful.

With regard to the dimensioning of the longitudinal grooves arranged at a distance from the rear face, is preferably the distance between the facing ends of the longitudinal grooves 0.2 to 0.8 times, the distance between the rear Front side and the end facing this of the longitudinal groove closer to the rear front side the C, 3 to 1 times and the length of a longitudinal groove 1.2 to 3 times the diameter of the insertion end.

The dimensioning of the longitudinal groove open to the rear face has been based on the common ones on the To judge the chucks on the market and therefore has a preferred length that is 3 to 12 times the diameter of the spigot end. Expressed in absolute numbers, all common chucks are recorded if the longitudinal groove open to the rear face has a length of about 4 5 mm.

Also based on the common chucks on the market, the spigot has three or a multiple of three longitudinal grooves open to the rear face with equal angular spacings.

Preferably those are open towards the rear face Longitudinal grooves formed V-shaped in cross section and the longitudinal grooves arranged at a distance from the rear end face substantially circular arc-shaped in cross-section. After the jaws of the commercially available chucks of impact drills have an angle of 120 °, the V-shaped cross-section can be used for the rear end face, i.e., an identical one in open longitudinal grooves Include angle or this angle can be slightly smaller, ie it can be between 100 and, for example Move 120 °. By reducing this angle, the mounting of the drilling tools is improved.

The invention is now intended to reproduce, for example, on the basis of it Drawings are explained in more detail, namely show:

1 shows the insertion end of a drilling tool according to the invention;

FIG. 2 shows a section along the line H-II of FIG. 1;

3 shows the insertion end of a further drilling tool according to the invention?

FIG. 4 shows a section along the line IV-IV of FIG.

FIGS. 1 and 2 show the insertion end 2 of a drilling tool designated as a whole by 1. As in particular Fig. 2 shows, this insertion end 2 has three evenly distributed over the circumference towards the rear face 3 open longitudinal grooves 4. This towards the free end face 3

open longitudinal grooves 4 have a V-shaped cross section. These are symmetrically open towards the free end face 3 Longitudinal grooves 4 overlapped by spaced apart from the rear face 3 longitudinal grooves 5, which an axially limited Have length. As the two figures make clear, are along an open to the rear face 3 towards Longitudinal groove 4 two closed longitudinal grooves 5 arranged one behind the other.

After the cross-sectional area of the to the rear face 3 longitudinal grooves 4 open towards the cross-sectional area of the spaced apart from the rear face 3 Longitudinal grooves 5 is smaller, shoulder surfaces 6, 7 are formed in the transition region. These shoulder surfaces 6, 7 delimit the axial displaceability when using such a drilling tool 1 in rotary hammers, the rotary hammers in known Way have a chuck with adjustable jaws.

In particular, that of the rear face is decisive remote shoulder surface 6, as this occurs when the drilling tool 1 is lifted from the substrate material to be processed the impact of the hammer piston on the hammer piston still acting on the drilling tool 1 must be intercepted. the opposite shoulder surface 7, however, is hardly stressed exposed, as this direction of movement counteracts the blows of the hammer piston.

As illustrated in FIGS. 1 and 2, they point to the rear End face 3 open towards the longitudinal grooves 4 a continuous groove base, which is also at a distance from the rear end face 3 arranged longitudinal grooves 5 penetrated. Thanks to this continuous groove base, the Use of the drilling tools 1 with such a spigot end 2 in hammer drills in any case a centric guide comes about regardless of the axial position of the clamping jaws of the chuck.

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FIGS. 3 and 4 show a drilling tool, denoted as a whole by 11, with an insertion end 12. As FIG. 4 in particular shows, the insertion end 12 has three longitudinal grooves 14 of V-shaped cross-section, evenly distributed over the circumference and open towards the rear face 13. Along a longitudinal groove 14 open towards the rear end face 13, two closed longitudinal grooves 15 arranged one behind the other are arranged at a distance from the rear end face 13. These longitudinal grooves 15, which are arranged at a distance from the rear face 13, are offset in the direction of rotation of the drilling tool 11 with respect to the longitudinal grooves 14 open towards the rear face 13, in such a way that the offset angle oL of the symmetry aclis of the longitudinal grooves 14, 15 is approximately 8 to 15 ° . In the transition area of the two longitudinal grooves 14, 15 there are again shoulder surfaces 16, 17 which, thanks to the offset arrangement, have an asymmetrical design.

As already pointed out above, the shoulder surface facing away from the rear end face 13 is in particular 16 for the drilling tool 11 when used in rotary hammers of decisive importance. When the longitudinal grooves 14, 15 are offset in the sense described, this occurs asymmetrically arranged facing away from the rear end face 13 Shoulder surface 16 to lie on the side where due to the torque acting on the drilling tool Mass come to the plant.

Thanks to this offset arrangement of the longitudinal grooves 14, 15 can the shoulder surface 16 facing away from the rear end face 13 are greatly influenced in terms of their size. On the one hand this can be done by varying the size of the cross-sectional areas and, on the other hand, by the degree of offset. So it is possible, for example, that despite the same cross-sectional training, one is still sufficient thanks to the transfer large shoulder surface 16 comes about.

The offset of the longitudinal grooves 14, 15 also has the consequence / that both in front of and behind as well as between the at a distance longitudinal grooves 15 arranged from the rear end face in spite of the presence of the towards the rear end face 13 open longitudinal groove 14 a sufficient proportion of the surface contour of the insertion end 12 remains. Like Fig. 4 in particular shows, in these areas about half the width of the surface contour is at the distance from the rear end face 13 arranged longitudinal grooves 15 left. This leads to the fact that, thanks to this remaining surface contour, the tool 11 is guided into the known, adjustable clamping jaws having chucks of rotary hammers remains in the same way, as if there were no longitudinal grooves 14 open towards the rear end face 13. This guidance on the surface contour is particularly significant when using drilling tools 11 of larger diameter in rotary hammers Meaning. The wear of the insertion end 12 can thereby be significantly reduced and thus the concentricity of the drilling tool 11 can be improved.

Claims (1)

HILTI AKTIENGESELLSCHAFT IN SCHAAN Principality of Liechtenstein Claims 1. Drilling tool for hand drills, with an essentially cylindrical spigot end, characterized by the combination of the following Characteristics: a) the insertion end (2, 12) has one or more open to the rear end face (3, 13) Longitudinal grooves (4, 14); b) the insertion end (2, 12) has one or more at a distance from the rear end face (3, 13) arranged longitudinal grooves (5, 15); c) to the rear end face (3, 13) open (4, 14) and longitudinal grooves (5, 15) arranged at a distance from the rear end face (3, 13) overlap in their axial projection with the formation of a shoulder surface facing away from the rear end face (3, 13) (6, 16) at least partially. W “.» ._ »« It * · ■ »« ■> - - · ■ - - - Tool according to Claim 1, characterized in that the cross-sectional area of the longitudinal grooves (A, 14) open towards the rear end face (3, 13) essentially corresponds to the cross-sectional area of the longitudinal grooves (5, 15) arranged at a distance from the rear end face (3, 13) ) is equivalent to. 3. Tool according to claim 1, characterized in that the cross-sectional area of the longitudinal grooves (4, 14) open towards the rear end face (3, 13) is smaller than that Cross-sectional area of the longitudinal grooves (5, 15) arranged at a distance from the rear end face (3, 13). 4. Drilling tool according to claim 3, characterized in that the rear end face (3, 13) is open Longitudinal grooves (4, 14) and at a distance from the rear Front side (3, 13) arranged longitudinal grooves (5, 15) to each other with coincident cross-sectional axes of symmetry are arranged. 5. Drilling tool according to one of claims 1 to 3, characterized in that the to the rear end face (3, 13) towards the open longitudinal grooves (4, 14) counter to the direction of rotation of the drilling tool to the at a distance from the rear end face (3, 13) arranged longitudinal grooves (5, 153 are staggered. 6. Drilling tool according to one of claims 1 to 5, characterized in that along one to the rear End face (3, 13) open towards the longitudinal groove (4, 14) one or more at a distance from the rear end face (3, 13) arranged longitudinal grooves (5, 15) are provided. Drilling tool according to Claim 6, characterized in that along one of the front faces (3, 13) to the rear longitudinal groove (4, 14) open towards two at a distance from the rear end face (3, 13) arranged longitudinal grooves (5, 15) are provided. 8. Drilling tool according to claim 6 or 7, characterized in that the distance (A) between the facing Ends of the longitudinal grooves (5, 15) arranged at a distance from the rear end face (3, 13) by 0.2 to 0.8 times the diameter of the insertion end (2, 12). 9. Drilling tool according to one of claims 6 to 8, characterized characterized in that the distance (B) between the rear end face (3, 13) and the one facing it End of the rear end face (3, 13) closer spaced longitudinal groove (5, 15) the 0.3 to 1 times the diameter of the spigot end (2, 12). 10. Drilling tool according to one of claims 1 to 9, characterized characterized in that the length (L) of a longitudinal groove arranged at a distance from the rear end face (3, 13) (5, 15) is 1.2 to 3 times the diameter of the spigot end (2, 12). 11. Drilling tool according to one of claims 1 to 10, characterized characterized in that the length (M) of a longitudinal groove (4, 14) open towards the rear end face (3, 13) is the 3 to 12 times the diameter of the spigot end (2, 12). 12. Drilling tool according to one of claims 1 to 11, characterized characterized that over the circumference of the insertion end (2, 12) with equal angular distances three or a multiple of three longitudinal grooves (4, 14) open towards the rear end face (3, 13) are provided. 13. Drilling tool according to one of claims 1 to 12, characterized in that the longitudinal grooves (4, 14) open towards the rear end face (3, 13) are V-shaped in cross-section at an included angle {ß) between 100 and 120 ° are. 14. Drilling tool according to one of claims 1 to 13, characterized characterized in that the longitudinal grooves (5, 15) arranged at a distance from the rear end face (3, 13) are formed in cross-section substantially in the shape of a circular arc.